This invention relates to a method for forming a metal termination at the end of a wound capacitor section and more particularly to the metal spray deposition of capacitor terminals.
It is well known to apply by spraying low melting temperature metals such as zinc, alloys of aluminum and solders to the ends of a wound capacitor section. This method is indeed the only practical termination method for use in some wound capacitors having metallized thermoplastics dielectric layers. The spray method conventionally employed is critical in that the molten metal particles impacting the end of such a capacitor must impact the exposed edges of an electrode with sufficient force and at a sufficient temperature to remove the oxide from the electrode edge and to make a sound electrical connection between the sprayed metal and the electrode. At the same time, the molten metal particles must not impact the thermoplastic dielectric material with so great a force and at so high a temperature that substantial physical distortion and damage occurs along the thermoplastic edge. It is particularly difficult to apply a thick and strong metal termination to such a capacitor because the temperature of the section end rapidly reaches destructively high values. It is conventional to apply a series of thin layers with long waiting times between layers to achieve the desired thickness and strength.
It is therefore an object of this invention to provide a method for the metal spray deposition of a termination to a wound capacitor requiring a minimum of handling and having a minimum number of steps.
It is a further object of this invention to provide a rapid low cost method for depositing a metal termination to an end of a wound capacitor section which section has heat sensitive dielectric layers.